JP2002055092A - Method and apparatus for diagnosing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such the problem that conventionally ultrasonic waves are used in a diagnostic apparatus, constituted so that a sound transmitter and a sound receiver are arranged on the surface of concrete structure or the like, and acoustic elastic waves are transmitted to the interior of an object to be inspected and a receiving signals is analyzed to investigate and internal structural flaw, directionality is sharp and a range capable of being inspected at one transmitter position is narrow, and for example, in the inspection of a wide range, such as the wall surface of a tunnel or the like, a long time is required and there is restriction is the arrangement of the transmitter and the receiver. SOLUTION: Frequency which is 100 Hz-100 kHz lower than conventional is used. First, the frequency characteristics of an object 101 to be inspected are measured within this frequency range and frequency wherein a receiving signal becomes large is calculated. Next, the object 101 to be inspected is excited for a prescribed time by the calculated frequency, to measure the attenuation characteristics of vibration. Sound velocity is calculated from the calculated attenuation characteristics and the data base 113 of the attenuation characteristics and the sound velocity preliminarily calculated with respect to a similar material and the compression strength of the object to be inspected is calculated from a data base 113 of preliminarily calculated sound velocity and compression strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure diagnosis method for finding an internal defect such as a concrete structure by measuring its internal acoustic characteristics, or estimating its acoustic velocity and compressive strength, and a structure thereof. The present invention relates to an object diagnostic device.

[0002]

2. Description of the Related Art First example. FIG. 10 is a configuration diagram showing a first example of a conventional structure diagnostic apparatus. In the drawing, reference numeral 401 denotes an inspection object such as concrete, and 402 denotes one surface 401a of the inspection object 401.
403 is a receiving signal amplifier for amplifying a signal from the receiving element 402, and 404 is an A for converting an output signal of the receiving signal amplifier 403 into a digital signal.
/ D converter. Reference numeral 405 denotes a transmitter mounted in close contact with one surface 401 a of the inspection object 401 (the same surface on which the receiver 402 is mounted), and 406 denotes a signal generator for sending a signal to the transmitter 405. Reference numeral 407 denotes a waveform processing mechanism for performing signal processing on the received signal (echo signal waveform or simply echo) digitized by the A / D converter 404 to obtain necessary acoustic characteristics. Reference numeral 408 denotes a display device for displaying a diagnosis result, and 409 denotes a storage device for storing the diagnosis result.

Next, the operation will be described. An elastic wave pulse in a high frequency band (ultrasonic range) is propagated from the transmitter 405 to the inside of the inspection object 401, and an abnormal portion in the inspection object 401 is transmitted.
The echo reflected by the defective part (not shown) is detected by the receiver 402, and the characteristic of the echo signal (magnitude, time deviation from the transmission signal, time width, change in frequency component, etc.) is determined based on the characteristic of the abnormal part. Estimate size, position and type.

[0004] Second example. FIG. 11 is a configuration diagram showing a second example of a conventional structure diagnostic apparatus. In the figure, reference numeral 501 denotes an object to be inspected such as concrete; 502, a receiver mounted in close contact with one surface 501a of the object 501; 503, a reception signal amplifier for amplifying a signal from the receiver 502; Inspection object 501
A transmitter 505 is provided in close contact with another surface 501b (a surface facing the surface on which the receiver 502 is provided), and a signal generator 505 for sending a signal to the transmitter 504. Reference numeral 506 denotes a trigger signal from the signal generator 505 and the received signal amplifier 5.
This is a propagation time measuring device that receives a signal from the device 03 and calculates a propagation time inside the object 501 based on a timing shift. Reference numeral 507 denotes a diagnostic processing mechanism,
01, a sound speed (signal propagation speed, hereinafter also referred to as an acoustic speed) is calculated, and the diagnostic database 50 is calculated.
The compression strength of the inspection object 501 is estimated on the basis of the information extracted from 8 (the relationship between the sound speed and the compression strength of various similar structures is checked in advance). Reference numeral 509 denotes a display device for displaying a diagnosis result, and 510 denotes a storage device for storing the diagnosis result.

Next, the operation will be described. Inspection object 50
11, an acoustic wave pulse propagated from the transmitter 504 contacting one surface 501a is detected by the receiver 502 contacting the opposing surface 501b, and the propagation time and the propagation distance determined in advance (in the case of FIG. 11) Is calculated from the thickness of the object 501). Next, based on the relationship between the sound speed and the compression strength obtained in advance based on the obtained sound speed (stored as the diagnostic database 508),
The compression strength of the inspection object 501 is estimated and displayed on the display device 509. Further, the presence or absence of an abnormal part is displayed based on whether or not the difference between the estimated compressive strength and the compressive strength of the test object 501 in a normal state exceeds a certain limit.

[0006]

Since the conventional structure diagnostic apparatus is configured as described above, the first example uses a high-frequency pulse, so that the structure of the abnormal part is a heterogeneous substance. However, there is a problem in that the elastic wave is greatly attenuated, and it is difficult to detect a reflected wave from an abnormal portion of the inspection object, so that the method cannot be applied. Further, therefore, it is necessary to transmit a large amount of energy that overcomes the attenuation, and there is a problem that the device becomes large and expensive. Further, there is a problem that the directivity is sharp and the range that can be diagnosed at one transmitter position is extremely narrow, and it takes a lot of time to inspect a wide range such as a tunnel wall. In addition, since the directivity is sharp, there is a restriction on the positional relationship between the transmitter and the receiver, for example, they must be arranged on the same plane.

In the second example, the distance between the transmitter and the receiver (elastic wave propagation distance) must be obtained in advance, but it may not be obtained depending on the structure of the structure. There was a problem that the sound velocity could not be measured (diagnosis itself could not be performed). In addition, when the transmitter and the receiver cannot be installed on the two opposing surfaces of the object due to the structure of the object, the diagnosis itself cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Diagnosis can be performed by transmitting a small amount of energy using a frequency with low attenuation, and the arrangement of a transmitter and a receiver is restricted. Therefore, there is no need to measure the distance between them (propagation distance), it is possible to arrange and measure on any two surfaces of the test object, and to measure the wide area of the test object at one transmitter position. It is an object of the present invention to obtain a structure diagnosis device capable of performing the above.

[0009]

According to the present invention, there is provided a method for diagnosing a structure, comprising the steps of installing a transmitter and a receiver on the surface of an object to be inspected, and applying a transmission signal to the transmitter while sweeping its frequency. Performing FFT analysis on a signal received by the receiver while applying the transmission signal to the transmitter, detecting one or more peak frequencies, and transmitting the signal at the peak frequency. To the child for a predetermined time,
After the cutoff, a procedure for measuring the attenuation characteristic of the signal received by the receiver, and comparing the measured attenuation characteristic with the attenuation characteristic of a normal test object measured in advance, and when the difference exceeds a predetermined range. This includes a procedure for determining an abnormality.

[0010] The method further includes a step of setting the transmitter and the receiver on the non-parallel surfaces of the surface of the inspection object.

Further, the method includes a step of estimating the compression strength or the sound speed of the inspection object from the measured attenuation characteristics and a database stored in advance.

A structure diagnostic apparatus according to the present invention includes a transmitter and a receiver installed on the surface of an object to be inspected, a frequency characteristic measuring circuit for performing a frequency sweep oscillation and outputting a transmission signal, and a circuit for measuring a specified frequency. A signal generator for transmitting a signal to the transmitter, the signal generator including a circuit for measuring an attenuation characteristic for performing oscillation, a switching circuit for selecting one of the circuit for measuring the frequency characteristic and the circuit for measuring the attenuation characteristic, and the receiver Analyzes the received signal, the waveform processing apparatus to obtain the frequency at which a large received signal is obtained, and the attenuation characteristics of the test object, the attenuation characteristics and sound speed of a material similar to the material constituting the test object A first database indicating the relationship between the compression characteristics and the attenuation characteristic or the sound velocity of a material similar to the material constituting the inspection object.
And a diagnostic processing device for obtaining the compression strength and sound speed of the inspection object from the attenuation characteristics obtained by the waveform processing device and the data of the first and second databases.

The frequency of the sweep oscillation transmitted by the frequency characteristic measuring circuit to the transmitter is between 100 Hz and 100 kHz, and the frequency transmitted by the attenuation characteristic measuring circuit to the transmitter is a single frequency within the frequency of the sweep oscillation. It uses one frequency.

Further, the waveform processing apparatus performs FFT conversion on the signal received by the receiver, detects a plurality of peak frequencies from the one having the largest frequency component, and sets the peak frequency as the frequency of the attenuation characteristic measuring circuit. Is obtained by averaging a plurality of attenuation time constants obtained for each of a plurality of frequencies to obtain an attenuation characteristic of the inspection object.

Further, the attenuation characteristic measuring circuit applies the sine wave of the peak frequency obtained from the waveform processing device to the transmitter for a predetermined time, stops the application, and then the waveform processing device The attenuation characteristic of the received signal is calculated by measuring the attenuation time of the received signal.

Further, the attenuation characteristic measuring circuit applies the sine wave of the natural frequency of the object to be inspected to the transmitter for a predetermined time, and stops the application. Is the result of measuring the decay time of the received signal of the receiver and calculating the attenuation characteristic.

The diagnostic processing device calculates the sound speed in the test object based on the measured decay time and a previously obtained diagnostic database.

The diagnostic processing device estimates the compressive strength inside the test object based on the measured decay time and the diagnostic database obtained in advance.

Further, the transmitter and the receiver are provided on surfaces of the inspection object which are not parallel to each other.

Further, the waveform processing apparatus performs an FFT conversion on the signal received by the receiver, detects one peak frequency from the FFT, sets the peak frequency as the frequency of the attenuation characteristic measuring circuit, and obtains the peak frequency corresponding to the peak frequency. The obtained attenuation time constant is used as the attenuation characteristic of the inspection object.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram of a structure diagnostic apparatus according to the present invention. In the figure, 101
Is an inspection object such as concrete, and 102 is an inspection object 10
1, a receiving element closely mounted on one surface 101b; 103, a receiving signal amplifier for amplifying a receiving signal of the receiving element 102;
An A / D converter 04 converts the output of the reception signal amplifier 103 into a digital signal. 105 is the inspection object 101
Is a transmitter closely mounted on another surface 101a (the surfaces 101a and 101b are not parallel to each other), and 106 is a signal generator for transmitting a transmission signal to the transmitter 105. The signal generator 106 includes a frequency characteristic measuring circuit 107, an attenuation characteristic measuring circuit 108, and a switching circuit 109 for selecting one of the two circuits. Signal generator 106
Is controlled by the measurement control device 110. 111 is A /
A waveform processing mechanism (waveform processing device) that analyzes and processes the signal waveform digitized by the D converter 104. 1
Reference numeral 12 denotes a diagnosis processing mechanism (diagnosis processing device) which estimates the sound speed, compression strength, and the like of the inspection object 101 from the processing result of the waveform processing device 111 and the diagnosis database 113. 11
4 is a display device for displaying analysis results and diagnosis results, 115
Is a storage device for storing analysis results and diagnosis results.
Here, the transmitter 105 and the receiver 102 may be installed in parallel on the same plane.

Hereinafter, the operation of the structure diagnostic apparatus of FIG. 1 will be described. FIG. 2 is a flowchart showing a diagnosis procedure. First, the test object 101 to be diagnosed in step S01
, A transmitter 105 and a receiver 102 are installed. Here, the positional relationship between the transmitter 105 and the receiver 102 is determined by the inspection object 101.
Need not be the same surface, and may be installed at an arbitrary place (on two surfaces 101a and 101b having different angles as shown in FIG. 1). Therefore, the measurement can be performed even when the transmitter 105 and the receiver 102 cannot be installed on the opposite surface of the inspection object 101 or when they cannot be installed on the same surface. It does not depend on the installation situation. This procedure includes a procedure according to the present invention, in which the components are installed on non-parallel surfaces of the surface of the inspection object. Of course, the following operation does not change even if the sensors are installed on parallel surfaces.

Next, in step S02, the signal generator 10
6 switching circuit 109, the frequency characteristic measuring circuit 10
7 is selected, and the transmission signal is oscillated by frequency sweep to vibrate the DUT 101. This procedure is a procedure for applying a transmission signal to the transmitter according to the present invention while sweeping its frequency. FIG. 3 shows a transmission signal of the frequency sweep. FIG.
In (a) and (b), the horizontal axis is the same time axis, the vertical axis in FIG. (A) is the current value of the drive current, and the vertical axis in FIG. (B) is the frequency. In the example shown in FIG.
A drive signal whose frequency continuously changes from 00 Hz to about 100 kHz) is shown. Here, the manner of change may be a straight line, an upwardly convex curve, or an upwardly concave curve, but it is assumed that the change is uniform. Of course, you may sweep from a high frequency to a low frequency. This transmission signal is transmitted to the inspection object 101 by the transmitter 105, and the inspection object 10
One response is detected by the receiver 102.

Next, in step S03, the signal obtained by the receiver 102 is subjected to FFT analysis by the waveform processing mechanism 111 to obtain a frequency spectrum. FIG. 4 shows an example of the obtained frequency spectrum. The vertical axis in the figure is a proportional scale of the amplitude.
From a plurality of peaks (shown as reference numerals 71, 72, 73, and 74 in FIG. 4) taken in descending order of the peak of the frequency spectrum, the test object 101 and the probe (the transmitter 105 and the receiver 102) were included. Find the natural frequency of the system. The structure of the test object 101 is various and has many resonance modes, and it is not generally used for a structure that easily resonates acoustically. Therefore, the natural frequency often appears at several points or more. Next, in step S04, one or a plurality of low-frequency ranges of several hundred Hz to several tens of kHz that have a high reception level among these natural frequencies are determined. For example, in FIG. 4, 71 is selected. In this example, the frequency of the natural frequency 71 is 3.5 kHz. Since the transmission frequency is a natural frequency in a low frequency range of 100 Hz to 100 kHz, it is possible to measure a test object having a large attenuation or a wide range. This procedure corresponds to the procedure of the present invention in which a signal received by a receiver while a transmission signal is applied to the transmitter is subjected to FFT analysis to detect one or more peak frequencies. Of course, if the natural frequency is known in advance, the measurement for determining the transmission frequency in steps S02 to S04 need not be performed.

Next, using the determined frequency of the natural frequency 71, the transmitter 105 applies vibration for a predetermined period of time (for example, 0.5 seconds as an example) in step S05, and then stops applying vibration. First, the switching circuit 109 selects the attenuation characteristic measuring circuit 108 of the signal generator 106. The attenuation characteristic measuring circuit 108 outputs the drive signal shown in FIG. In FIG. 5, the drive signal is a sine wave of the frequency 71 determined previously, and is a continuous wave of a fixed time length that is turned on at time t1 and turned off at time t2. This drive signal is output to the transmitter 105.
Here, since a sinusoidal wave is used for transmission at a single frequency, an elastic wave can be efficiently propagated to the inspection object 101.

Next, in step S06, the attenuation characteristic of the received signal obtained by the receiver 102 after the excitation is stopped is determined. The response of the test object 101 is detected by the receiver 102. The desired damping characteristic is a damping time constant in the free vibration time domain. One procedure for detecting the attenuation characteristic is described below. FIG. 6 shows an example of a received signal detected by the receiver 102 (an example of the natural frequency 71 (3.5 kHz) shown in FIG. 4).
Is shown. In FIG. 6, t2 corresponds to the signal-off time point t2 in FIG. The attenuation characteristic is calculated from the response after the signal is turned off t2.
Here, an attenuation time constant is measured as the attenuation characteristic. In general, since the attenuation characteristic shows a tendency of logarithmic attenuation, displaying the reception level on a logarithmic axis as shown in FIG. 7 makes it easier to detect the attenuation characteristic as a linear change. The explanation auxiliary line 11 in the figure is an approximation line that approximates the damping vibration amplitude with a straight line. From this approximation line, the decay time constant τ is calculated as follows. The coordinates of arbitrary two points P3 and P4 taken on the straight line 11 in FIG. 7 are (t3, y3), and
(t4, y4)

[0027]

(Equation 1)

Is obtained. Now, in the example of FIG.
3 (101.6 ms, 0.350), P4 (102.7
ms, 0.071), so that τ = 0.69 ms is calculated. The above analysis and calculation are performed by the waveform processing mechanism 111. The procedure of steps S05 and S06 refers to the present invention.
This corresponds to a procedure in which a signal of the peak frequency is applied to the transmitter for a predetermined time, and after the signal is cut off, the attenuation characteristic of the signal received by the receiver is measured.

Next, in step S07, whether or not to detect the presence or absence of an abnormal portion is selected. If so, in step S08, it is determined whether or not the obtained attenuation characteristic, that is, the attenuation time constant, is abnormal by comparing with the normal value stored in the diagnosis database 113 (or the recorded past measurement result). Find out. For example, if the obtained decay time constant in the free vibration time domain is more than a predetermined difference from the decay time constant of the normal part, it is estimated that the part is abnormal. If abnormal, the inspection object 101 is determined in step S09.
From the data stored in the diagnosis database 113 (or the recorded past determination result), a more detailed determination such as a determination of a material of an abnormal portion is performed. This processing is performed by the diagnosis processing mechanism 112.

When estimating the compressive strength and sound speed of the inspection object after step S10, the data (database 11) is determined by using the attenuation characteristics obtained in steps S08 to S09 as indices.
3) Estimate from FIG. 8 shows the free vibration time domain (transmitter 1
FIG. 11 is a diagram (referred to as a first database) showing a relationship between a damping time constant and a sound speed in the vibration after stopping the excitation in FIG. When it is known that there is a relationship indicated by a black dot in FIG. 8 between the damping time constant and the sound velocity in the free vibration time domain,
Data gaps are complemented in advance to obtain a data curve indicated by a dotted line. (Step S11) From this figure, the sound velocity of the test object 101 can be estimated from the obtained attenuation time constant in the free vibration time domain. (Step S1
2) Similarly, the correlation between the compressive strength and the decay time constant or the sound speed in the free vibration time domain is obtained in advance as shown in FIG. 9 (second database). (Step S13) Then, the compression strength is estimated from the obtained attenuation time constant or sound speed. (Step S14) FIG. 9 is a diagram showing the relationship between the speed of sound and the compressive strength.

It has been found that the attenuation characteristic depends on the frequency. Therefore, the accuracy of the diagnosis item can be improved by obtaining the attenuation characteristics at the plurality of determined frequencies and performing averaging.

Next, a procedure for constructing the database 113 will be described. As the database 113, core samples having different acoustic velocities (test sample)
Prepare a large number of and measure the acoustic velocity of each core,
Based on the above description, the damping time constant is measured, the compressive strength is measured, and the data is further complemented to construct the database 113 in which the correlation between the two is clarified. As a means for obtaining core samples having different acoustic velocities, coring is performed from various structures, and a collection of core samples in which the acoustic velocities are distributed is obtained by collecting the cores.
Furthermore, for example, there is a method in which many types of concrete cores having different water-cement ratios are manufactured, and the acoustic velocity, the damping time constant, and the compressive strength are measured. FIGS. 8 and 9 show an example of a database constructed by complementing data sampled from actual structures. It goes without saying that the diagrams of the damping time constant and the compressive strength can be easily obtained from FIGS.

Next, the procedure of diagnosis will be described. In the above description, the attenuation time constant of the test object 101 for which the diagnosis has been performed is obtained. Therefore, the acoustic velocity corresponding to the attenuation time constant of the test object 101 is obtained from the database of the attenuation time constant and the acoustic velocity shown in FIG. By reading the data, the acoustic velocity can be predicted. For example, the decay time constant is 0.69 m
If it is s, the predicted value of the obtained acoustic velocity is 3533 m / s (as shown by the dotted line in FIG. 8). If the range of the sound speed of the normal sample is checked in advance, the diagnosis as to whether or not the inspection object is normal can be made from the viewpoint of the sound speed based on the above-described results.

On the other hand, by further applying the correlation database between the acoustic velocity and the compressive strength (FIG. 9), the compressive strength value corresponding to the obtained acoustic velocity value is obtained as 19 N / mm ^2, and is obtained from the attenuation time constant. It is possible to predict the strength of the inspection object 101, and a diagnosis can be made from this aspect.

[0035]

As described above, according to the method for diagnosing a structure of the present invention, the procedure for detecting the peak frequency of the object to be inspected, the procedure for measuring the attenuation characteristic at this peak frequency, and the method for detecting the attenuation characteristic only with the attenuation characteristic are used. Since the procedure includes a procedure for diagnosing an abnormality of the inspection object, the operation and effect of performing diagnosis and inspection with a relatively low transmission signal can be obtained.

Since the transmitter and the receiver are arranged so as not to be parallel to each other, the installation of the transmitter and the receiver is less restricted, and the operation and effect that the transmitter and the receiver can be easily installed can be obtained.

Further, since a procedure for determining the sound speed or the compressive strength from the attenuation characteristics is included, an operation and effect that can estimate the type of abnormality of the inspection object can be obtained.

According to the structure diagnostic apparatus of the present invention, an abnormal portion of the inspection object is detected and the compression strength and the sound speed are estimated from the attenuation characteristics of the signal obtained by the receiver, so that the inspection object is not destroyed. The measurement can be performed on any surface of the inspection object without accompanying.

Further, since the transmission frequency is in a low frequency range of about 100 Hz to about 100 kHz and the natural frequency of the object to be inspected is used, the signal can be efficiently propagated to the object to be inspected. An object can be measured, and there is an effect that a wide range can be measured at one transmitter position.

Further, measurement is performed at a plurality of peak frequencies,
Since the attenuation characteristic is obtained from the average of the obtained multiple attenuation time constants,
The effect of improving accuracy is obtained.

In the attenuation characteristic, since the free vibration is measured after applying the sine wave of the peak frequency for a predetermined time, it is possible to obtain an effect of performing diagnosis and inspection with a relatively low transmission signal.

Since the attenuation characteristic measures the free vibration after applying a sine wave of the natural vibration frequency of the object to be inspected for a predetermined time, diagnosis and inspection can be performed with a relatively low transmission signal. The operation and effect are obtained.

Further, since the sound velocity of the inspection object is measured, it is possible to know the abnormality of the internal structure in more detail.

Further, since the compressive strength of the inspection object is measured, it is possible to know the abnormality of the internal structure in more detail.

Further, since the transmitter and the receiver are allowed to be installed on surfaces that are not parallel to each other, the effect of increasing the degree of freedom in installation can be obtained.

Further, measurement is performed at one peak frequency,
Since the damping characteristic is obtained from the obtained damping time constant, the operation and effect that the configuration can be simplified can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a structure diagnostic apparatus according to the present invention.

FIG. 2 is a flowchart showing a diagnostic procedure according to the present invention.

FIG. 3 is a diagram illustrating a drive signal for frequency sweep.

FIG. 4 is a diagram illustrating an example of a frequency spectrum obtained by a receiver.

FIG. 5 is a diagram showing a drive signal for measuring attenuation characteristics.

FIG. 6 is a diagram illustrating an example of a time response obtained by a receiver.

FIG. 7 is a diagram illustrating an example of calculating a time response attenuation characteristic obtained by a receiver.

FIG. 8 is an example diagram of a database showing a relationship between a decay time and a sound speed.

FIG. 9 is a diagram showing an example of a correlation database between acoustic velocity and compression strength.

FIG. 10 is a configuration diagram showing a first example of a conventional structure diagnosis apparatus.

FIG. 11 is a configuration diagram showing a second example of a conventional structure diagnostic apparatus.

[Description of Signs] 101 inspected object, 102 receiver, 103 receiver amplifier, 105 transmitter, 106 signal generator, 10
7 Frequency characteristic measurement circuit, 108 Attenuation characteristic measurement circuit, 109 switching circuit, 111 waveform processing device, 112 diagnostic processing device, 113 diagnostic database.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Shimada 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Koichiro Kai 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Rishi Electric Co., Ltd. (72) Inventor Shuichi Nakamura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Yoshinobu Yamaguchi 2-4-2, Shibata, Kita-ku, Osaka-shi, Osaka West Within Japan Railway Company (72) Inventor Seiichi Matsui 2-4-2, Shibata, Kita-ku, Osaka-shi, Osaka West Japan Railway Company F-term (reference) 2G047 AA10 BB00 BC03 BC04 BC09 BC20 GF11 GG12 GG19 GG24 GG36

Claims (12)

[Claims] 1. a step of installing a transmitter and a receiver on the surface of an object to be inspected; a step of applying a transmission signal to the transmitter while sweeping its frequency; and applying the transmission signal to the transmitter. While performing a FFT analysis of the signal received by the receiver, detecting one or more peak frequencies, applying a signal of the peak frequency to the transmitter for a predetermined time, after the cutoff, A procedure for measuring the attenuation characteristic of the signal received by the receiver, comparing the measured attenuation characteristic with the attenuation characteristic of a normal test object measured in advance, and determining that the difference is abnormal when the difference exceeds a predetermined range. A method of diagnosing a structure, comprising a procedure. 2. The method according to claim 1, further comprising a step of installing the transmitter and the receiver on surfaces that are not parallel to each other on the surface of the inspection object. 3. The structure diagnosis method according to claim 1, further comprising a step of estimating a compression strength or a sound velocity of the inspection object from the measured attenuation characteristics and a database stored in advance. . 4. A transmitter and a receiver mounted on the surface of an object to be inspected, a frequency characteristic measuring circuit for outputting a transmission signal by performing frequency sweep oscillation, and an attenuation characteristic measuring circuit for oscillating at a specified frequency. A signal generator for transmitting a transmission signal to the transmitter, including a circuit and a switching circuit for selecting one of the frequency characteristic measurement circuit and the attenuation characteristic measurement circuit, and analyzing the signal received by the receiver. And a waveform processing apparatus that obtains a frequency at which a large received signal is obtained and an attenuation characteristic of the object to be inspected, and a relationship between the attenuation characteristic and sound speed of a material similar to the material constituting the object to be inspected. A first database, a second database indicating a relationship between any one of the attenuation characteristic or the sound speed and a compression strength for a material similar to the material constituting the inspection object, Structure diagnostic apparatus characterized by the data of the attenuation characteristic and the first and second databases, with the diagnostic processor for determining the compressive strength and the speed of sound the inspection object. 5. The sweep frequency of a transmission signal transmitted by the frequency characteristic measurement circuit to the transmitter is between 100 Hz and 100 kHz, and the frequency transmitted by the attenuation characteristic measurement circuit to the transmitter is within the frequency of the sweep oscillation. The structure diagnostic apparatus according to claim 4, wherein a single frequency is used. 6. A waveform processing device which performs FFT conversion on a signal received by a receiver, detects a plurality of peak frequencies in descending order of the frequency component, and sets the peak frequency as a frequency of an attenuation characteristic measuring circuit. The structure diagnostic apparatus according to claim 4, wherein a plurality of attenuation time constants obtained corresponding to each of the plurality of frequencies are averaged to obtain an attenuation characteristic of the inspection object. 7. The attenuation characteristic measuring circuit applies a sine wave having a peak frequency obtained from the waveform processing device to a transmitter for a predetermined time, and after the application is stopped, the waveform processing device causes the receiver to The structure diagnostic apparatus according to claim 6, wherein the attenuation characteristic is calculated by measuring an attenuation time of the received signal. 8. A waveform processing apparatus for applying a predetermined characteristic sine wave of a natural frequency of an object to be inspected to a transmitter for a predetermined period of time, and stopping the application of the sine wave. 7. The structure diagnostic apparatus according to claim 6, wherein the measuring unit calculates an attenuation characteristic by measuring an attenuation time of a reception signal of the receiver. 9. The structure diagnosis apparatus according to claim 7, wherein the diagnosis processing device calculates a sound speed in the inspection object based on the measured attenuation time and a diagnosis database obtained in advance. . 10. The structure according to claim 7, wherein the diagnosis processing device estimates the compression strength inside the test object based on the measured decay time and a diagnosis database obtained in advance. Diagnostic device. 11. The structure diagnostic apparatus according to claim 4, wherein the transmitter and the receiver are provided on surfaces of the inspection object that are not parallel to each other. 12. A waveform processing apparatus performs FFT conversion on a signal received by a receiver, detects one peak frequency from the signals, sets the detected peak frequency as a frequency of an attenuation characteristic measuring circuit, and responds to the peak frequency. The structure diagnostic apparatus according to claim 4, wherein the obtained attenuation time constant is used as an attenuation characteristic of the inspection object.